Lightning Bolt is the most efficient spell beginning shaman have--I really don't know how you were OOMing unless you chain-pulled more than 5 or 6 mobs. Earth Shock's damage debuff is worth having, but Earth Shocking on cooldown will run you out of mana fairly quickly--it's basically double a lightning bolt in damage & mana. Primal Strike's damage-to-mana ratio is worse than LB/ES, so it's really best used as a finisher.

Rolling Thunder is unavaiable until level 20, therefore, you do not regain mana back when casting LB. LB is then suddenly mana costly.